Avoid duplicate paths in qemu binary list

Fix #204

gns3server/modules/qemu/__init__.py

@@ -47,13 +47,13 @@ class Qemu(BaseManager):
         """
 
         qemus = []
-        paths = []
+        paths = set()
         try:
-            paths.append(os.getcwd())
+            paths.add(os.getcwd())
         except FileNotFoundError:
             log.warning("The current working directory doesn't exist")
         if "PATH" in os.environ:
-            paths.extend(os.environ["PATH"].split(os.pathsep))
+            paths.update(os.environ["PATH"].split(os.pathsep))
         else:
             log.warning("The PATH environment variable doesn't exist")
         # look for Qemu binaries in the current working directory and $PATH
@@ -64,21 +64,21 @@ class Qemu(BaseManager):
                 exec_dir = os.path.dirname(os.path.abspath(sys.executable))
                 for f in os.listdir(exec_dir):
                     if f.lower().startswith("qemu"):
-                        paths.append(os.path.join(exec_dir, f))
+                        paths.add(os.path.join(exec_dir, f))
 
             if "PROGRAMFILES(X86)" in os.environ and os.path.exists(os.environ["PROGRAMFILES(X86)"]):
-                paths.append(os.path.join(os.environ["PROGRAMFILES(X86)"], "qemu"))
+                paths.add(os.path.join(os.environ["PROGRAMFILES(X86)"], "qemu"))
             if "PROGRAMFILES" in os.environ and os.path.exists(os.environ["PROGRAMFILES"]):
-                paths.append(os.path.join(os.environ["PROGRAMFILES"], "qemu"))
+                paths.add(os.path.join(os.environ["PROGRAMFILES"], "qemu"))
         elif sys.platform.startswith("darwin"):
             # add specific locations on Mac OS X regardless of what's in $PATH
-            paths.extend(["/usr/local/bin", "/opt/local/bin"])
+            paths.update(["/usr/local/bin", "/opt/local/bin"])
             if hasattr(sys, "frozen"):
                 try:
-                    paths.append(os.path.abspath(os.path.join(os.getcwd(), "../../../qemu/bin/")))
+                    paths.add(os.path.abspath(os.path.join(os.getcwd(), "../../../qemu/bin/")))
                 # If the user run the server by hand from outside
                 except FileNotFoundError:
-                    paths.append(["/Applications/GNS3.app/Contents/Resources/qemu/bin"])
+                    paths.add("/Applications/GNS3.app/Contents/Resources/qemu/bin")
         for path in paths:
             try:
                 for f in os.listdir(path):